| # Licensed to the Apache Software Foundation (ASF) under one |
| # or more contributor license agreements. See the NOTICE file |
| # distributed with this work for additional information |
| # regarding copyright ownership. The ASF licenses this file |
| # to you under the Apache License, Version 2.0 (the |
| # "License"); you may not use this file except in compliance |
| # with the License. You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, |
| # software distributed under the License is distributed on an |
| # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| # KIND, either express or implied. See the License for the |
| # specific language governing permissions and limitations |
| # under the License. |
| """Compatibility layer for different database engines |
| |
| This modules stores logic specific to different database engines. Things |
| like time-related functions that are similar but not identical, or |
| information as to expose certain features or not and how to expose them. |
| |
| For instance, Hive/Presto supports partitions and have a specific API to |
| list partitions. Other databases like Vertica also support partitions but |
| have different API to get to them. Other databases don't support partitions |
| at all. The classes here will use a common interface to specify all this. |
| |
| The general idea is to use static classes and an inheritance scheme. |
| """ |
| import inspect |
| import logging |
| import pkgutil |
| from collections import defaultdict |
| from importlib import import_module |
| from pathlib import Path |
| from typing import Any, Dict, List, Set, Type |
| |
| import sqlalchemy.databases |
| import sqlalchemy.dialects |
| from pkg_resources import iter_entry_points |
| from sqlalchemy.engine.default import DefaultDialect |
| |
| from superset.db_engine_specs.base import BaseEngineSpec |
| |
| logger = logging.getLogger(__name__) |
| |
| |
| def is_engine_spec(attr: Any) -> bool: |
| return ( |
| inspect.isclass(attr) |
| and issubclass(attr, BaseEngineSpec) |
| and attr != BaseEngineSpec |
| ) |
| |
| |
| def get_engine_specs() -> Dict[str, Type[BaseEngineSpec]]: |
| engine_specs: List[Type[BaseEngineSpec]] = [] |
| |
| # load standard engines |
| db_engine_spec_dir = str(Path(__file__).parent) |
| for module_info in pkgutil.iter_modules([db_engine_spec_dir], prefix="."): |
| module = import_module(module_info.name, package=__name__) |
| engine_specs.extend( |
| getattr(module, attr) |
| for attr in module.__dict__ |
| if is_engine_spec(getattr(module, attr)) |
| ) |
| |
| # load additional engines from external modules |
| for ep in iter_entry_points("superset.db_engine_specs"): |
| try: |
| engine_spec = ep.load() |
| except Exception: # pylint: disable=broad-except |
| logger.warning("Unable to load Superset DB engine spec: %s", engine_spec) |
| continue |
| engine_specs.append(engine_spec) |
| |
| # build map from name/alias -> spec |
| engine_specs_map: Dict[str, Type[BaseEngineSpec]] = {} |
| for engine_spec in engine_specs: |
| names = [engine_spec.engine] |
| if engine_spec.engine_aliases: |
| names.extend(engine_spec.engine_aliases) |
| |
| for name in names: |
| engine_specs_map[name] = engine_spec |
| |
| return engine_specs_map |
| |
| |
| def get_available_engine_specs() -> Dict[Type[BaseEngineSpec], Set[str]]: |
| """ |
| Return available engine specs and installed drivers for them. |
| """ |
| drivers: Dict[str, Set[str]] = defaultdict(set) |
| |
| # native SQLAlchemy dialects |
| for attr in sqlalchemy.databases.__all__: |
| dialect = getattr(sqlalchemy.dialects, attr) |
| for attribute in dialect.__dict__.values(): |
| if ( |
| hasattr(attribute, "dialect") |
| and inspect.isclass(attribute.dialect) |
| and issubclass(attribute.dialect, DefaultDialect) |
| ): |
| try: |
| attribute.dialect.dbapi() |
| except ModuleNotFoundError: |
| continue |
| except Exception as ex: # pylint: disable=broad-except |
| logger.warning( |
| "Unable to load dialect %s: %s", attribute.dialect, ex |
| ) |
| continue |
| drivers[attr].add(attribute.dialect.driver) |
| |
| # installed 3rd-party dialects |
| for ep in iter_entry_points("sqlalchemy.dialects"): |
| try: |
| dialect = ep.load() |
| except Exception: # pylint: disable=broad-except |
| logger.warning("Unable to load SQLAlchemy dialect: %s", dialect) |
| else: |
| drivers[dialect.name].add(getattr(dialect, "driver", dialect.name)) |
| |
| engine_specs = get_engine_specs() |
| return { |
| engine_specs[backend]: drivers |
| for backend, drivers in drivers.items() |
| if backend in engine_specs |
| } |